Natural radioactivity has no effect on us.  But on the contrary, atomic energy used for industrial and military purposes produces artificial radioactivity, which pollutes the environment and the human body.  Medical radiotherapy constitutes another source of radiation.  The radioactive substances are heavy metals and this implies that chlorella can eliminate them.  People exposed to strong activity should take 10 gr of chlorella every day (p.62).  If chlorella cannot repair damages caused to healthy tissues by radioactive rays, it can eliminate the radioactive substances, and this is highly recommended.